How To Cut Stone for Natural Stone Walls

Hardscaping projects that look rough-hewn and “natural” often require a great deal of cutting and shaping stone. To combine a rustic look with a solid structure, stones must often fit together like a jigsaw puzzle. Roger Cook, This Old House’s expert landscaper, consults with Trow & Holden stoneworker Randy Potter to showcase different techniques for cutting and shaping stones. Below, we’ll outline those techniques and give you tips for using both power tools and hand tools.

Tools for Cutting Stone for Walls

As you might expect, the tools you’ll need depend on the type of cuts or modifications you want to make. Here are some of the necessary tools and what you’ll use them for:

• Creating clean cuts: Circular saw or angle grinder with a diamond-tipped masonry blade, clamps, and chalk.
• Safety equipment: Safety glasses, work gloves, and dust mask.
• Shaping and removing protrusions: Carbide-tipped handpoint, mallet, bushing hammer.
• Splitting large stones: Rotary hammer drill, carbide-tipped masonry bit, depth gauge, wedges, shims (also called feathers), and masonry hammer.
• Splitting medium stones: Stone buster and 3-pound mini sledgehammer.
• Splitting small stones: Hand tracer and 3-pound mini sledgehammer.
• Trimming stone edges: Handset and 3-pound mini sledgehammer.

Cutting Stone With Power Tools

Power tools swiftly handle cutting larger stones or making precise cuts. Below are two common methods for cutting stones using these tools.

Using a Circular Saw or Angle Grinder

Although Cook and Potter don’t demonstrate this method in the video, you can achieve clean and precise cuts with power saws. However, you’ll need to ensure the saw or grinder has sufficient power for the type of stone. Porous stones such as limestone and travertine will require less power than stones such as granite and marble.

Here are some steps for using a circular saw or angle grinder:

1. Mark the cutting line on the stone with chalk or a pencil.
2. Secure the stone with clamps.
3. Put on safety glasses, a dust mask, and work gloves.
4. If using a circular saw, adjust the blade depth to 1/2 an inch.
5. Use the saw or angle grinder to trace the cutting line lightly, making a shallow groove to act as a guide for deeper cuts.
6. Guide the saw or grinder slowly along the marked line, allowing the blade to work effectively.
7. For thicker stones, make multiple passes if necessary. Take breaks to prevent the power tool from overheating.

Pro tip: Use firm, steady pressure with the saw or grinder to minimize chipping. It’s also better to make multiple shallow cuts than to attempt too deep a cut and get the blade stuck.

Using an Electric Rotary Hammer and Wedges

To split or make a large stone and create a usable face, you’ll first need to drill holes using a rotary hammer. Then you can set your wedges and shims.

Here are all the steps:

1. Use chalk to mark the cut you intend to make.
2. Adjust the depth.
3. Drill holes spaced 4 inches apart using the rotary hammer fitted with a masonry bit.
4. Insert the shims into each hole, with the ears pointed in the direction you want the stone to break.
5. Insert steel wedges snugly between the shims.
6. Tap each wedge with a hammer, alternating between wedges so that the pressure exerted by each remains roughly equal. Use the sound of the hammer strike to guide you.
7. Continue increasing pressure gradually until the stone splits.

Pro tip: Even with directed pressure, stones split along natural flaws that you often can’t see from the outside. The downside of making rough cuts and splits is that, as Potter inadvertently demonstrates, the stone might not split the way you intend. Having extra stones on hand can save you a lot of frustration.

Hand Tools for Cutting and Shaping Stone for Walls

Power tools are undoubtedly efficient, but hand tools provide better control and can produce a more rustic-looking aesthetic.

Using a Hand Tracer

For smaller stones or more delicate cuts, the hand tracer is ideal:

1. Chalk your cutting line on the stone.
2. Hold the tracer vertically against the stone where you need to cut.
3. Tap the tracer with a hammer, slightly moving it after each tap to etch a line across the material.
4. Gradually increase the force with each tap until the stone splits.

Using a Stone Buster

The stone buster is effective for dealing with medium-sized stones:

1. Chalk your cutting line.
2. Position the stone buster along the desired cutting line.
3. Strike it sharply with a hammer, moving along the stone after each strike.
4. Continue until the stone fully splits.

Pro tip: As Potter mentions, you can swing the stone buster for more power rather than tapping it with a hammer. This will give you more power but far less control over the direction of the split. Note that despite his experience, Potter says even he’s “not that good yet.”

Trimming and Shaping Stones

To refine a stone’s shape or to remove protrusions, switch to a handset, hand point, and bushing hammer, and use these steps:

1. Use a carbide handset at an angle to the stone’s edge.
2. Strike the handset with a hammer to chip small stone pieces away.
3. For larger protrusions, employ a carbide-tipped hand point for expedited removal.
4. Smooth surfaces using a bushing hammer, tapping lightly to attain the desired finish.

Tips for Successful Stone Cutting and Shaping

Achieving mastery in stone cutting and shaping requires patience and practice. Consider these tips:

• Always use high-quality and high-durability hammers and saw blades that are rated for use with stone. Given the forces involved, low-quality tools could be safety hazards.
• Approach the work methodically, avoiding damage and unwanted cracks.
• Begin with lighter taps, gradually increasing force as necessary. Excessive force applied rapidly can fracture the stone in unpredictable ways rather than splitting it neatly.
• Consistently wear safety glasses and gloves to guard against flying chips.
• Hone techniques by practicing on scrap pieces before using main project stones.
• Use the stone’s natural grain and flaws to aid in splitting larger pieces.

Our Conclusion

Everything presented here is a general tip for stone splitting, but a key aspect of working with natural stone is recognizing its unique characteristics. Each type of stone has distinct properties that affect how it is cut and shaped, dictating the choice of tools and methods. For instance, softer stones such as limestone require different handling than harder stones like granite. And, of course, individual stones within a particular type have their own variations. 

Stonework is a specialty field, and you may need to do some research and talk to experts to get the results you want. Always remember to prioritize safety and exercise patience with these unique landscaping materials and tools.

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